At Home In The Woods

[Obed]

We had several conversations with the framer and truss designer about the subflooring for the attic/upstairs. The house is a story and a half. However, we have no intentions of finishing the upstairs. We don't need the space nor do we really want to have to clean and maintain it. If we ever decided to sell the house we would most likely finish the upstairs to increase the resale value.

Thus, we really didn't want subflooring in the upstairs/attic. The attic floor trusses are 18" high, 19.2" O.C. We intend to use blown insulation above the main floor ceiling. Doing so will give us better insulation coverage than batting. We also would like easy access to the truss area below the attic and above the main floor ceiling for ease of running future wiring, etc. I'd rather not have to punch holes in the main floor ceiling to later add a light, ceiling fan, surround-sound speaker, etc.

On the other hand, the framer really wanted subflooring up there to make it easy for him to install the stick-built roof. The truss designer was encouring us to put 3/4" Advantech subflooring upstairs to stabilize the attic floor trusses. Note: The truss designer works for the building supply company and I'm sure also wants to sell us the subflooring.

We ended up buying cheap 7/16" OSB to use as attic subflooring. Each sheet will be screwed to the trusses with a screw in 4 corners and with one screw per truss down the middle for structural support. We will need to temporarilly remove some of the subflooring sheets when we blow insulation in the floor trusses and for running main floor ceiling wiring. The OSB subflooring will not be glued to the trusses. The cost of the 3/4" Advantech that the truss designer wanted to sell us would have been over $1200. The cost for the OSB was $400.

If we ever decided to finish the upstairs, we would add another 7/16" layer of OSB subflooring on top of the existing OSB. Keep in mind that we would only finish the upstairs in order to sell the house.

 

[radioman]

Sounds like a game plan for the what if in the future with thinner osb. The only thing I would be concerned with is how far they screw in the screws. if they countersink too far it due to being soft, its gonna be a bear find them and out, but then its too late to think about that.

 

[mikefromnh]

You will be glad to have a floor for storage. And it will save a lot of time framing the roof.

Make sure they use good quality screws such as 'Deck-mate' or other good brand name. Commodity (the kind you get out of hardware store bins) dry wall and deck screws will snap/strip easily.

 

[gpflepsen]

Whoa... I suggest strongly to put down 3/4" OSB or tongue and groove plywood. You want a stable surface that can take a load without flexing. Imagine carrying 100 lbs and stepping midspan at the edge of the thinner 7/16" OSB. I bet some audible cracking would be heard. Put down one layer of subfloor and be done would be my preference. I would definitely put something down to stabilize the trusses. The drywall ceiling will thank you for that alone.

Why are you insulating the floor, sound management? I would think the attic would be the place for thermal insulation. In the future if you want access to the truss area below the upper floor for insulating or fixture installation, you can always remove the screws and lift the subfloor from the area needing the access.

 

[nhkabotab7800]

i agree that you would be better off using something thicker than 7/16" osb 5/8" even would be better. perhaps 3/4" osb but not Advantec i understand your desire to save money and that you will not really be on the second level, but 1/2" osb is just too thin to span 2 foot on center trusses.

 

[Duffster]

i agree that you would be better off using something thicker than 7/16" osb 5/8" even would be better. perhaps 3/4" osb but not Advantec i understand your desire to save money and that you will not really be on the second level, but 1/2" osb is just too thin to span 2 foot on center trusses.

The floor trusses are 19.2 oc.

7/16 will work, you got to remember that with the floor trusses on that spacing there is only 15.7" between the trusses.

 

[FallbrookFarmer]

I think that you are going to have some bounce in the floor with 7/16 OSB, but if you ARE going to go with it, I would suggest making some sort of marks as to where you are screwing it down to the OSB. That way, if you decide to add another layer, you will be able to hit the trusses, when you screw/nail down the next layer.

 

[2manyrocks]

For what it might cost in the future to add another layer of OSB, I would go ahead and sheet the attic floor properly now and be done with it. Think about having to haul in 4x8 sheets of material into your attic space after your house is finished.

 

[gpflepsen]

For what it might cost in the future to add another layer of OSB, I would go ahead and sheet the attic floor properly now and be done with it. Think about having to haul in 4x8 sheets of material into your attic space after your house is finished.

What's the old saying... "penny wise, pound foolish".

 

[sld]

For what it might cost in the future to add another layer of OSB, I would go ahead and sheet the attic floor properly now and be done with it. Think about having to haul in 4x8 sheets of material into your attic space after your house is finished.

That is a very good point! Spend a few hundred to do it right.

Easy for me to say.

 

[eepete]

When you're in the thick of the "fog of construction", each day brings a $50 to $500 decision to make. And sooner than you think your budget cushion is wearing thin. So I'm just going to wish Obed the best of "luck" making these decisions and trade offs. I know he values the feedback, but only he is in the position to make the call.

Regarding this particular issue, I hope there is a window somewhere on the floor in question where a boom truck could deliver 4x8 sheets years down the road. Failing that, I hope there is some way to maneuver the sheets in later through the house. If there is, then the 7/16 is a fine choice and it saves money that will no doubt be needed later for things that will come up that are "now or never" decisions.

Obed, still liking the thread, loving the pix, and smiling because I now how nice it is to "get out of the mud" on a house project.

Pete

 

[dcyrilc]

When you're in the thick of the "fog of construction", each day brings a $50 to $500 decision to make. And sooner than you think your budget cushion is wearing thin. So I'm just going to wish Obed the best of "luck" making these decisions and trade offs. I know he values the feedback, but only he is in the position to make the call.

Regarding this particular issue, I hope there is a window somewhere on the floor in question where a boom truck could deliver 4x8 sheets years down the road. Failing that, I hope there is some way to maneuver the sheets in later through the house. If there is, then the 7/16 is a fine choice and it saves money that will no doubt be needed later for things that will come up that are "now or never" decisions.

Obed, still liking the thread, loving the pix, and smiling because I now how nice it is to "get out of the mud" on a house project.

Pete

Ditto here.
...and dying to hear the rest of the story about the eviction.

 

[Obed]

We really wish we didn't have to have any subflooring upstairs. I'd be happy with nothing but floor trusses up there. We have plenty of storage space in the basement. Main floor = 2100 SF. We expect we will eventually finish the basement for a mother-n-law suite. Potential basement living space = 1200 SF plus a single car garage and unfinished utility room/storage area. We don't need any more space. We want all our living space on one floor (i.e. ranch) even though the house looks like a 1 1/2 story house from the outside.

A ranch house has a large footprint and thus a large attic area. There is 1700 SF available in the "attic" that could be finished as living space. But we don't need or even want that space for living. In fact, we have changed some things so the tax appraisers don't call the attic "potential" living space and jack up our tax appraisal. We originally had plans for a nice staircase going from our foyer entrance to a door that would open into the unfinished attic. Unfortunately, if we put in the stairs, the tax folks will add 1700 SF to the recorded house square footage and increase our property taxes by 50%. So we are going install a wall to close up the area where the staircase would have gone. We can easily tear out the wall and put in a staircase later if we choose. We are installing pull-down steps in the garage ceiling for accessing the attic. I would love to have regular stairs to the attic but don't want the property tax increase.

The other factor to which I have previously alluded is the ability to have easy access to the area above the main floor ceiling. How would we blow the insulation over the main floor ceiling with 3/4" tongue-n-grove subflooring glued and screwed on top of it? Also, it's not fun to open up the ceiling sheetrock for repairs or to run wiring for things for which you didn't originally plan. Patching the ceiling frequently leaves visible marks. With the 7/16" OSB partially screwed down in the attic, we will have access to what ever we need. We can add wiring for surround sound in the living room, add a ceiling fan, run Cat 6 wiring, etc. whenever we choose.

Yes, we can get more 4x8 sheets of subflooring to the upstairs in the unlikely event that we finish the upstairs.

 

[mikefromnh]

Regarding the future stairs:

Have your or are you framing a closet where the stairs would be. You could put the door to the closet where the bottom of the 'stairs' land. Later on it is a simple matter to open the door, rip out the ceiling and frame the stairs.

You can never have enough storage! And walk up attic storage is a luxury. Makes being organized much easier.

It wasn't that long ago that it was common practice to sheet the whole house with 1/2", frame the interior and then double the ply where carpet or tile is going. Hardwood flooring (3/4" t+g) would go directly on the single layer of ply. That way all the floor heights would line up pretty well.

 

[grainger12002]

Obed
My best wishes and absolute good luck(!) with the decisions that come daily on your new home construction project. Not much to add as most has been said I just want to say good luck and try to enjoy the project. As with all things there are good and bad in every day,dwell on the good,dont let the GC or others wear on you.
All the best,stay warm and as close to budget as possible !!
From Eastern,CT

 

[nhkabotab7800]

Obed, in light of recent posts perhaps just a "Cat Walk" down the center? That would alow easy blow in insulation, and access later if needed, as well as saving some money on materials.

 

[Obed]

Obed, in light of recent posts perhaps just a "Cat Walk" down the center? That would alow easy blow in insulation, and access later if needed, as well as saving some money on materials.

A "cat walk" would have been great. However, the truss designer strongly recommended subflooring the entire attic for structural support. So that's the way we went.

Obed

 

[dcyrilc]

A "cat walk" would have been great. However, the truss designer strongly recommended subflooring the entire attic for structural support. So that's the way we went.

Obed

Pix? How's the weather been since the snow? Looks like the current storm's passing north of you.

 

[buckeyefarmer]

I "stocked" some 5/16" osb in my attic when I built. I eventually spread them out, but they aren't nailed down so I can easily move them if I need to. I put about 4 sheets too many up there, they are sometimes in my way.

 

[2manyrocks]

I used to live in a house that had finished flooring in the center of the attic to make it easy to walk on, but nothing in the areas where the pitch of the rafter joists made it difficult to stand fully upright. It also had a nice finished wood staircase (built in a straight run, too) which always struck me as odd because the staircase wasn't really in a public area of the house. The house was built in the early 1900's when builders didn't try to squeeze staircases into compact sizes like today. The finished attic flooring wasn't of the same grade as the finished flooring on the main floor, however.

No one knows for sure which way this economy is headed. In the past, I'd have said advantech won't get any cheaper in the future. I think the day is quickly coming when the attic would make a good play space for your child. Then......